1. Field of the Invention
The present invention relates to a mode change over device for a camera, and more particularly to a safety means which prevents mode change over at certain camera settings.
2. Description of the Prior Art
Generally, cameras which are capable of operating in different photographing modes may be equipped to operate in the shutter time photographing mode, the aperture value preference photographing mode, the program photographing mode and the manual photographing mode. Also, the camera may be capable of a light measuring mode change over involving change over from the fully opened light measuring mode to the diaphragm closed light measuring mode. Furthermore, cameras are known which are capable of effecting both the photographing mode change over and the light measuring mode change over. Such known cameras are provided with a safety device in order to avoid erroneous selection of the modes. The type of erroneous selection contemplated might involve noncompatible mode selection such as selection of the diaphragm closed light measuring mode while in the shutter time preference photographing mode. One approach for preventing such erroneous selection involves the use of devices to mechanically prevent such errors. Thus, the operation of the change over means which is considered to cause the erroneous selection of the modes is prohibited and made impossible. However, in many cases, undue load is often imposed on the change over member because the photographer tries to continuously operate the operation member without recognizing that such operation has been made impossible. As a result, the durability of the member becomes a problem, and in the worst case, the camera is damaged. According to a second preventive measure which is applicable to a camera which is electrically released, the selection of the erroneous photographing mode is electrically deflected to prohibit the release operation. However, in many existing safety devices, problems arise because, while improper selection is prevented, there nevertheless arise other problems which may cause the loss of a photographic opportunity.
It is an object of the present invention to overcome the above shortcomings by providing a mechanism wherein the diaphragm closing button for selecting the diaphragm closed light measuring mode is rendered inoperative in the case where the camera is set in the shutter time preference photographing mode.
It is another object of the present invention to provide a mechanism which operates to set the manual photographing mode when, in the case where the camera is set in the diaphragm closed light measuring mode, the shutter time preference photographing mode is selected by mistake.